An investigation of the catalytic mechanism of a readily available brain glycosidase, the aglycone-nonspecific beta-galactosidase of bovine brain, using techniques already developed for the bacterial enzyme (cf. M.L. Sinnott, FEBS Lett., 1978, 94, 1). An investigation of the aglycone-specific enzyme from the same source, based on the chemical synthesis of the aglycone.